Plunger type electro-magnetic pump



p 1956 J. w. DICKEY ETAL 2,764,098

PLUNGER TYPE ELECTRO-MAGNETIC PUMP Filed Oct. 28, 1953 nymvrozes QM W00 BY ,2: WI TNESS United States Horseheads, N. Y., assignors to Bendix Aviation Corporation, a corporation of Delaware Application Uctober 28, 1953, Serial No. 388,778 4- Claims. (Cl. Ki-53) The present invention relates to a plunger type electromagnetic pump and more particularly to a solenoid oper ated fuel pump for internal combustion engines.

Electromagnetic pumps of the type illustrated for in stance in the patent to Dickey et al. 2,472,067, issued June 7, 1949, have attained marked commercial success under all normal conditions of use. It has been found possible, however, to load up the liquid to be pumped with suspended material which is so finely divided that it will pass through the commercial types of filter, and may impair or even stop the action of the pump. When such dust or mud is of an abrasive character, the reciprocation of the plunger in its cylinder in the presence of such material is also conducive of accelerated wear and erosion of the parts.

It is an object of the novel electro-magnetic plunger pump which will operate indefinitely in spite of the presence of a high degree turbidity and non-filterable suspended foreign matter.

It is another object to provide such a device which includes shielding or packing means for preventing the suspenetrating between the sliding surfaces of the pump plunger and cylinder.

It is another object to provide such a device in which the packing means is of such character that any particles which are not removed from the cylinder walls in advance of the piston are trapped or entrained in the packing material and thus rendered incapable of abrading or clogging the sliding surfaces.

Further objects and advantages will be apparent from the following description taken in connection with the accompanying drawing in which:

Fig. l is a vertical substantially mid-sectional view of a preferred embodiment of the invention, the electrical system being indicated diagrammatically; and

Fig. 2 is a slightly enlarged sectional detail of the plunger with its packing means.

In Fig. 1 of the drawing there is illustrated an electromagnetic plunger pump comprising a non-magnetic cylinder 1 in which a hollow plunger or piston 2 of magnetic material is reciprocated by means of an electro-magnet 3 and an operating spring 4. The operating assembly of cylinder, plunger, and actuating means is mounted in a casing it? having an inlet chamber 5 and outlet chamber 6; and check valves '7 and 8 in the inlet chamber and plunger respectively are operative to cause transfer of liquid through the plunger from the inlet chamber to the outlet chamber responsive to reciprocation of the plunger.

A cylindrical screen 9 in the inlet chamber 5 serves to filter the liquid as it leaves the inlet chamber.

Means for reciprocating the plunger 2 is provided comprising a battery 11, one terminal of which is grounded at 12, and the other terminal connected to one terminal of the electro-magnet 3, the opposite terminal of which is grounded intermittently through contacts 13.

The operation of the contacts to secure reciprocation of the plunger by the alternate action of elect-ro-magnet 3 atent 0 2,764,098 Patented Sept. 25, 1956 2 and spring 4 is the same as described in the patent to Dickey et a1. above cited and since it forms no part of the present invention, further description thereof is deemed unnecessary.

According to the present invention, the piston plunger 2 is provided at each end with a pair of nesting frustoconical surfaces. As best seen in Fig. 2, one such surface 14 is formed at the upper end of the plunger ass a flared opening which merges into a counterbore 15 forming a cylindrical socket or seat. The nesting or mating conical surface 16 is formed on a nipple 17 having a press fit in the cylindrical socket 15 of the plunger.

Similarly, at the lower end of the plunger, a flaring conical surface 18 is provided, and a mating conical surface 19 is formed on a thimble 21 which carries the check valve 8. The thimble 21 is anchored in the plunger by means of a cylindrical skirt 22 which fits snugly in an undercut groove 23 in the flared portion 18 of the plunger. Circumferentially spaced portions of the skirt 22 are forced laterally outward into the groove 23 as shown at 24 in order to securely anchor the thimble in the plunger. This is conveniently accomplished by means of a spider 25 which acts as a guide for the stem 26 of the check valve 8. Prior to assembly, the spider 25 is dished downwardly and fits snugly in the skirt 22 of thimble 21. When the parts are assembled, the spider 25 is flattened as illustrated, which causes its legs to expand the contiguous portion of the skirt as above set forth.

Between the conical surfaces l4, 16 at the upper end of the plunger 2, a disc of wool felt is inserted, which disc 27 is pressed into the shape of a truncated cone as the surfaces .14, 16 approach each other and clamp the inner portion of the disc between them during the assembly portion of the felt member projects peripheral diameter is of the plunger 2, and cylinder 1 the felt ring or squeegee action which leaves nothing on the cylinder wall as the plunger moves upward on its discharge stroke.

A similar felt ring 28 is likewise clamped between the nesting conical surfaces 18, 19 at the bottom of the plunger 2 and serves to pack the space between the surfaces of the plunger and the cylinder on the downward stroke of the plunger.

It has been found in practice that felt rings so installed cylinder. It appears that penetrate and lodge beneath the surface of the felt, whereby the smooth, nonabrasive action of the felt on the cylinder wall is preserved in spite of the presence of finely divided abrasive material in the liquid. This is evidenced by extended periods of operaticn in the presence of such abrasive material with negligible wear on the cylinder wall, whereas without the felt packing rings, the useful life of the pump under such circumstances is markedly shortened.

Although but one form of the invention has been shown and described in detail it will be understood that other embodiments are possible and changes may be made in the precise form and arrangement of the parts without departing from the spirit of the invention.

We claim:

1. In an electromagnetic plunger pump a non-magnetic cylinder, a hollow magnetic plunger having a loose sliding fit therein, electro-magnetic means for reciprocating the plunger, means whereby such reciprocation causes liquid to flow through the cylinder and piston, said piston having at each end a pair of nesting frusto-conical surfaces; and a felt swabber ring of substantially uniform thickness clamped between said surfaces and formed thereby into a conically flared collar with its outer periphery pressing elastically against the inner surface of the cylinder. 3

, 2. A plunger pump as set forth in claim 1 in which the conical felt collars are arranged to flame outwardly in the direction away from the body of the plunger and thereby be expanded by t-he resistance of the liquid to the motion of the plunger.

3. In an electromagnetic plunger pump a non-magnetic cylinder, a hollow magnetic plunger having a loose sliding fit therein, electro-magnetic means for reciprocating the plunger, means whereby such reciprocation causes liquid to flow through the cylinder and piston, said piston having at each end a frusto-conical flared opening merging into a cylindrical counter-bore, a cylindrical nipple fixedly mounted in said counterbore having a frusto-conical flared shoulder at its outer end conforming to said flared opening in the end of the piston, and a felt swabber ring clamped between said frusto-conical elements and held thereby in wiping contact with the inner surface of the cylinder.

4. An electromagnetic pump as set forth in claim 3 in which one of said counterbores has an undercut groove, and the nipple mounted therein has an internal valve seat, a check valve member movably mounted in the nipple to cooperate with the seat, and a spider forming a guide for the valve member, and an expander for anchoring the nipple in said counter-bore.

Dickey et a1. June 7, 1949 Payne June 21, 1949 

